Attractions Between Molecules

Question 0

Polarity

Answer 0

A polar intermolecular attraction can exist between two polar molecules. The slightly positive end of one molecule forms and electrostatic attraction to the slightly negative end of another molecule.

A hydrogen bond occurs when a hydrogen atom is involved with a polar intermolecular attraction to a more electronegative atom.

Polar intermolecular attractions are much stronger than Van der Waals forces.

Question 1

Van Der Waals forces

Answer 1

Van Der Waals forces are sometimes referred to as dispersion forces or “instantaneous dipoles.” These forces are created by the chance movement of electrons in a system of atoms bonded together.

The strength of attraction is proportional to the number of electrons in the molecule. These forces are weak relative to polar intermolecular forces, and they become apparent only if there are many electrons, or if the molecules come very close together.